WO2013103099A1

WO2013103099A1 - Method for separating and recovering rare-earth element

Info

Publication number: WO2013103099A1
Application number: PCT/JP2012/083256
Authority: WO
Inventors: 宮田　素之; 山本　浩貴; 佐々木　洋; 俊夫安田; 克佳古澤
Original assignee: 日立金属株式会社
Priority date: 2012-01-06
Filing date: 2012-12-21
Publication date: 2013-07-11
Also published as: JP5835349B2; US9376736B2; CN104053801A; US20140356258A1; CN104053801B; JPWO2013103099A1

Abstract

A method for separating and recovering a plurality of rare-earth elements, wherein the method comprises: a step for introducing into a liquid a mixture of a rare-earth oxychloride and rare-earth oxychloride, the rare-earth oxychloride constituted from a rare-earth element of a different type from a rare-earth element constituting the rare-earth chloride, thereby yielding an insoluble substance containing the rare-earth oxychloride and a liquid in which the rare-earth chloride is dissolved; a step for recovering the rare-earth oxychloride from the insoluble substance; and a step for recovering the rare-earth chloride from the liquid in which the rare-earth chloride is dissolved.

Description

Rare earth element separation and recovery method

The present invention relates to a method for separating and collecting rare earth elements, and more particularly to a method for separating and collecting rare earth elements from a composition containing a plurality of types of rare earth elements.

In recent years, the importance of sustainable global environmental conservation has been recognized, and the development of industrial systems, transportation systems, and products that can minimize the use of fossil fuels has been vigorously conducted. Examples of such environmentally compatible systems and products include wind power generation systems, railway systems, hybrid vehicles, and electric vehicles.

High-efficiency rotating electrical machines (motors and generators) are the main devices used in these environmentally compatible systems and products. In this high-efficiency rotating electric machine, a magnet containing a rare earth element (so-called rare earth magnet) is used. For example, a rare earth magnet used in a high-efficiency rotating electric machine of a hybrid vehicle is required to have a high coercive force even in a high temperature environment, and contains a rare earth element such as neodymium (Nd) or dysprosium (Dy). Rare earth magnets are used. Rare earth magnets are indispensable for high-efficiency rotating electrical machines, and demand is expected to increase further in the future.

On the other hand, due to soaring prices of rare earth raw materials due to the geographical uneven distribution of rare earth raw materials, methods for reducing the amount of rare earth components used in rare earth magnets and separating and recovering rare earth elements from used rare earth magnets are being studied. As an example of this separation and recovery method, there is a method of separating and recovering rare earth elements from shavings (sludge) generated in the manufacturing process of rare earth magnets or used waste magnets.

As a method for separating and recovering rare earth elements from a composition containing multiple types of rare earth elements such as rare earth magnets (hereinafter referred to as “rare earth composition”), Patent Document 1 discloses neodymium (Nd) and dysprosium (Dy). Separation using the difference in solubility of sulfate is described. Patent Document 2 describes a technique of acid leaching sludge and then solvent extraction. Patent Document 3 discloses a method of separating by utilizing the difference in properties between a divalent rare earth halide and a trivalent rare earth halide by halogenating a rare earth element in a mixture containing a plurality of rare earth elements or compounds thereof. Are listed. Patent Document 4 describes a method of separating and recovering rare earth elements as chlorides by reacting iron chloride with sludge or waste magnets.

JP 2010-285680 A JP 2009-249664 A JP 2001-303149 A Japanese Patent Laid-Open No. 2003-73754

In the methods described in Patent Document 1 and Patent Document 2, an extremely high concentration of strong acid or highly volatile solvent is used, and thus the influence on the global environment is not limited. The method described in Patent Document 2 requires a multi-stage separation because a single separation rate is not sufficient. The methods described in Patent Document 3 and Patent Document 4 have a problem that the rare earth separation rate is small.

An object of the present invention is to provide a method for separating and recovering rare earth elements, which has little influence on the global environment and can further increase the separation rate.

The rare earth element separation and recovery method according to the present invention has the following features. A method for separating and recovering a plurality of types of rare earth elements, comprising a rare earth oxychloride and a rare earth chloride, wherein the rare earth element is formed from a rare earth element different from the rare earth elements constituting the rare earth chloride. A step of obtaining an insoluble matter containing the rare earth acid chloride and a liquid in which the rare earth chloride is dissolved by adding the mixture comprising the material into the liquid; and the rare earth acid chloride from the insoluble matter. A step of recovering, and a step of recovering the rare earth chloride from the liquid in which the rare earth chloride is dissolved.

The method for separating and collecting rare earth elements according to the present invention can also have the following features. A method for separating and recovering a plurality of types of rare earth elements, which is a mixture including a first rare earth acid chloride and a second rare earth acid chloride, and a rare earth element constituting the second rare earth acid chloride, Obtaining a liquid in which the first rare earth acid chloride is dissolved by putting the mixture in which the first rare earth acid chloride is composed of different types of rare earth elements into the liquid; and A step of recovering the first rare earth acid chloride from the liquid in which the rare earth acid chloride is dissolved; and a step of recovering the second rare earth acid chloride from the insoluble material not dissolved in the liquid.

According to the present invention, a rare earth element can be separated and recovered from a rare earth composition with a high separation rate with little influence on the global environment. For example, it becomes possible to regenerate and use rare earth elements with a high separation rate from sludge generated in the manufacturing process of rare earth magnets and used waste magnets. For this reason, resources on the earth can be used effectively, and it can contribute to sustainable global environmental conservation.

Nd—O—Cl chemical potential diagram at 1000K. Dy-O-Cl chemical potential diagram at 1000K. The liquid, schematic view of a step of separating and recovering neodymium chloride (NdCl ₃₎ and dysprosium acid chloride (DyOCl). The schematic diagram of the process of isolate | separating and recovering neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) with a liquid. FIG. 3 is a diagram showing the amount of Dy contained in a liquid in Example 1. The figure which shows the Dy-separation rate of an insoluble matter in Example 1. FIG. The figure which shows the relationship between the amount of ethanol in the liquid in Example 2, and Dy isolation | separation rate of an insoluble matter. The figure which shows the Dy isolation | separation rate of an insoluble substance when the mixing ratio of the neodymium chloride and dysprosium acid chloride in Example 3 is changed. The figure which shows the Dy isolation | separation rate of an insoluble matter when the kind of liquid in Example 4 is changed. The X-ray-diffraction pattern of the powder obtained by heat processing of the mixed powder of neodymium oxide and neodymium chloride in Example 6. The X-ray-diffraction pattern of the powder obtained by heat processing of the mixed powder of the dysprosium oxide and dysprosium chloride in Example 6. FIG. The figure which shows the Nd amount and Dy amount of a solution at the time of changing the ethanol amount in a liquid in Example 6. FIG. The figure which shows the Dy isolation | separation rate of a solution at the time of changing the amount of ethanol in the liquid in Example 6. FIG. The figure which shows the relationship between the particle size of NdOCl and the amount of Nd of a solution in Example 7, and the relationship between the particle size of DyOCl and the amount of Dy of a solution. The figure which shows the Dy isolation | separation rate of a solution at the time of changing the particle size of NdOCl and DyOCl in Example 7. FIG. The figure which shows the Nd amount and Dy amount of a solution when the kind of liquid in Example 8 is changed. The figure which shows the Dy separation rate of a solution when the kind of liquid in Example 8 is changed.

Hereinafter, embodiments of the method for separating and recovering rare earth elements according to the present invention will be described in detail. Hereinafter, as a rare earth composition, a rare earth magnet (NdFeB magnet) containing neodymium (Nd), dysprosium (Dy) or the like will be taken as an example, and a method for separating and recovering Nd and Dy from this rare earth magnet will be described as an example.

However, the present invention is not limited to this example, and can be applied to, for example, a method for separating and recovering rare earth elements used in phosphors and cathode-ray tubes. In addition to Nd and Dy, other rare earth elements such as lanthanum (La), cerium (Ce), and praseodymium (Pr) can be separated and recovered. In the following, an example of separating and recovering two (Nd, Dy) rare earth elements contained in a rare earth composition will be described. However, the present invention includes three or more rare earth elements contained in the rare earth composition. Also, each rare earth element can be separated and recovered.

(1) Basic principle for separating and collecting rare earth elements The basic principle for separating and collecting rare earth elements is a method for separating and collecting Nd and Dy from a mixture of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl), and neodymium. A method for separating and recovering Nd and Dy from a mixture of acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) will be described as an example.

First, an example of a method for separating and recovering Nd and Dy from a mixture of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) will be described.

First, a method for producing neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) will be described. However, the present invention does not limit method for generating neodymium chloride (NdCl ₃₎ and dysprosium acid chloride (DyOCl), product neodymium chloride (NdCl ₃₎ and dysprosium acid chloride (DyOCl) in this way You don't have to.

FIG. 1A is an Nd—O—Cl chemical potential diagram, and FIG. 1B is a Dy—O—Cl chemical potential diagram. 1A and 1B, the horizontal axis represents the chlorine potential, and the vertical axis represents the oxygen potential. 1A and 1B show chemical potential diagrams at 1000 K as an example of typical temperatures.

In any chemical potential diagram, the oxide (Nd ₂ O ₃ , Dy ₂ O ₃ ) is stable in the region where the oxygen potential is high and the chlorine potential is low, and trivalent chloride is used in the region where the chlorine potential is high and the oxygen potential is low. In the region where (NdCl ₃ , DyCl ₃ ) is stable and both the oxygen potential and the chlorine potential are low, the metal (Nd, Dy) is stable. Furthermore, in the region of the chloride state where the chlorine potential is low, a divalent chloride state (NdCl ₂ , DyCl ₂ ) is observed between the metal state and the metal state. Further, a stable region of acid chloride (NdOCl, DyOCl) exists between the oxide region and the chloride region.

In the chemical potential diagrams of FIGS. 1A and 1B, neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) are fixed at a point A where the potential (partial pressure) of chlorine and oxygen is fixed. (NdCl ₃ ) and dysprosium chloride (DyOCl) coexist, and it is possible to produce a mixture of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) from a rare earth composition containing Nd and Dy Become.

By placing the mixture of the thus generated neodymium chloride (NdCl ₃₎ and dysprosium acid chloride (DyOCl) in the liquid, it is separated and recovered neodymium chloride (NdCl ₃₎ and dysprosium acid chloride (DyOCl) it can.

FIG. 2 is a schematic diagram of a process of separating and recovering neodymium chloride (NdCl ₃ ) and dysprosium oxychloride (DyOCl) with a liquid. As shown in FIG. 2, when a mixture 10 of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) is put in the liquid 20, the neodymium chloride (NdCl ₃ ) dissolves in the liquid 20, and the dysprosium chloride is (DyOCl) does not dissolve in the liquid 20 but becomes an insoluble material 30. In this way, a mixture 10 of neodymium chloride (NdCl ₃₎ and dysprosium acid chloride (DyOCl), neodymium chloride (NdCl ₃₎ and dysprosium acid chloride (DyOCl) can be separated and recovered.

Next, an example of a method for separating and recovering Nd and Dy from a mixture of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) will be described.

First, a method for producing neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) will be described. However, since the present invention does not limit the method for producing neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl), neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) are produced by this method. You don't have to.

In the chemical potential diagrams of FIGS. 1A and 1B, neodymium chloride is fixed by fixing the potential (partial pressure) of chlorine and oxygen in a region where neodymium chloride (NdOCl) and dysprosium chloride (DyOCl) are stable. (NdOCl) and dysprosium chloride (DyOCl) coexist and it becomes possible to produce a mixture of neodymium chloride (NdOCl) and dysprosium chloride (DyOCl) from a rare earth composition containing Nd and Dy. .

The mixture of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) produced in this way is put into a liquid, and the difference in solubility in the liquid is utilized to make use of the neodymium acid chloride (NdOCl) and dysprosium acid chloride. The product (DyOCl) can be separated and recovered.

FIG. 3 is a schematic diagram of a process for separating and recovering neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) using the difference in solubility in liquid. As shown in FIG. 3, when a mixture 40 of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) is placed in liquid 50, neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) are liquid 50. However, the solubility of the two is different. Due to the difference in solubility between the two, the amount of Dy and the amount of Nd in the liquid 50 are different. For example, as shown in FIG. 15 described later, when the liquid 50 is a mixed liquid in which 50% of an organic solvent is mixed with pure water, the amount of Dy in the liquid 50 is extremely larger than the amount of Nd. That is, in this case, dysprosium acid chloride (DyOCl) is dissolved in a large amount in the liquid 50, and neodymium acid chloride (NdOCl) is not so much dissolved (insoluble material 60). Thus, by utilizing the difference in solubility in liquid, neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) are separated and recovered from the mixture of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl). can do.

(2) Separation of rare earth elements and other elements from rare earth compositions From rare earth magnets mainly composed of neodymium (Nd), dysprosium (Dy), iron (Fe), and boron (B) (NdFeB magnets) A method for separating elements from other elements will be described. Here, as the raw material (rare earth composition) used for separation, it is preferable to use rare earth magnet waste, for example, waste, defective products, or processing scraps (sludge) such as cutting during magnet production. From the viewpoint of easy chemical reaction, the raw material is preferably in powder form. Below, the example isolate | separated from the powder of sludge is shown.

Examples of the method for separating rare earth elements from other elements include, but are not limited to, the following examples. In the first method, the sludge is heated to oxidize, water is added to the slurry to form a slurry, acid or alkali is added to the slurry, pH is adjusted, and components other than rare earth elements are precipitated as hydroxides. It is a method to make it. The second method is a method in which sludge powder is dissolved with sulfuric acid or the like and then components other than rare earth elements are separated by an oxalic acid precipitation method. In the third method, the sludge powder is heated in a chlorine atmosphere to form mixed chlorides, and then heated under reduced pressure, whereby the vapor pressure of each chloride (rare earth chloride, iron chloride, etc.). This is a method for separating rare earth elements from other elements by utilizing the difference between them. The fourth method is a method in which sludge powder is placed in a molten salt such as magnesium chloride or zinc iodide, and a rare earth element is chlorinated or iodinated and immersed to separate iron, boron, and the like.

Further, rare earth elements are recovered in the form of rare earth oxides, rare earth oxalates, rare earth carbonates, rare earth iodides, rare earth chlorides, rare earth sulfates, and the like by the above separation method. By using these as starting materials and adjusting the chlorine partial pressure and oxygen partial pressure in a chlorine atmosphere and performing heat treatment, desired rare earth chlorides and rare earth acid chlorides can be obtained. In the above example, neodymium chloride (NdCl ₃ ) and dysprosic acid are prepared by adjusting the chlorine partial pressure and the oxygen partial pressure at point A shown in FIGS. 1A and 1B and heat-treating the starting material in a chlorine atmosphere. Chloride (DyOCl) can be obtained. Further, the starting material is heated in a chlorine atmosphere by adjusting the chlorine partial pressure and the oxygen partial pressure in a region where neodymium chloride (NdOCl) and dysprosium chloride (DyOCl) shown in FIGS. 1A and 1B are stable. By doing so, neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) can be obtained.

(3) Separation of Dy and Nd When a mixture of neodymium chloride (NdCl ₃ ) and dysprosium acid chloride (DyOCl) is put into the liquid, as shown in FIG. 2, the neodymium chloride (NdCl ₃ ) dissolves in the liquid. Since dysprosium chloride (DyOCl) does not dissolve in the liquid and becomes insoluble, neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) can be separated and recovered. Moreover, when a mixture of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) is put into a liquid, the difference in solubility between neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) in the liquid is utilized. , Nd and Dy can be separated. As the liquid, pure water, a solution obtained by mixing an organic solvent in pure water, and an organic solvent can be used. As the organic solvent, alcohol is preferably used, and methanol or ethanol is particularly preferably used among the alcohols. These organic solvents are less volatile than the organic solvents used in Patent Document 1, Patent Document 2, and the like, and have little influence on the global environment.

As described above, Dy and Nd can be separated by putting a mixture of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) into a liquid, or neodymium chloride (NdOCl) and dysprosium chloride ( DyOCl) is put into the liquid. Here, it is preferable to stir the liquid according to the amount of the liquid and the amount of the mixture to be added. For stirring, for example, a stirring bar, a stirring blade, or ultrasonic vibration can be used. In addition, it is preferable that the agitation be performed in order to prevent the liquid from volatilizing. Elution into the liquid can be promoted by heating at the time of stirring. However, since the amount of the liquid decreases when the heating temperature becomes higher than the boiling point of the liquid, the temperature at the time of stirring is preferably not more than the boiling point of the liquid.

In the method of separating and recovering Nd and Dy from a mixture of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl), the ratio of Dy contained in insoluble matter that does not dissolve in the liquid is referred to as Dy separation rate. In the method of separating and recovering Nd and Dy from a mixture of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl), the ratio of Dy contained in the liquid (solution) is referred to as Dy separation rate. These Dy separation rates are represented by M _D / (M _N + M _D ) × 100, where the mass of Dy is M _D and the mass of Nd is M _N. When the Dy separation rate is large, Dy can be separated efficiently. The Dy separation rate is preferably 90% or more in one separation, and more preferably 95%.

(4) Recovery of Dy and Nd As described above, in the method of separating and recovering Nd and Dy from a mixture of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl), neodymium chloride (NdCl ₃ ) and dysprosium When a mixture of acid chlorides (DyOCl) is put into a liquid, a solution in which neodymium chloride is dissolved is obtained, and dysprosium acid chloride is obtained as a solid insoluble matter. In addition, insoluble matter may contain other components as impurities in addition to dysprosium chloride. A solution in which neodymium chloride is dissolved and an insoluble matter containing dysprosium chloride can be separated by a general method such as filtration or centrifugation.

With respect to the neodymium chloride solution, Nd can be recovered as a powder of neodymium chloride by spraying it in a heated atmosphere using a spray dryer. Or after adjusting pH with respect to a neodymium chloride solution, a slightly soluble neodymium salt is produced | generated by adding a precipitation material. Nd can be recovered as neodymium oxide by filtering and drying the insoluble matter and then baking at about 900 ° C. in the air. Examples of the precipitation material include ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), ammonium hydrogen carbonate (NH ₄ HCO ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), oxalic acid (( COOH) ₂ ), sodium oxalate ((COONa) ₂ ), ammonium hydroxide (NH ₄ OH), or the like can be used.

Dy can be recovered as dysprosium chloride by drying the dysprosium chloride obtained as a solid insoluble matter. Alternatively, by dissolving dysprosium acid chloride with an acid (for example, hydrochloric acid or nitric acid) to obtain a hydrate, adjusting the pH of the hydrate, and then adding a precipitation material, A slightly soluble insoluble substance of dysprosium salt is formed.

Further, as described above, in the method of separating and recovering Nd and Dy from a mixture of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl), neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) When the mixture is put into a liquid, a solution in which they are dissolved is obtained. Of the neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl), those not dissolved in the liquid precipitate as solid insolubles. The solution and the solid insoluble matter can be separated by a general method such as filtration or centrifugation.

Here, as an example, a case where a mixed solution in which 50% of an organic solvent is mixed with pure water is used as a liquid, that is, a case where the solution mainly contains Dy and an insoluble matter mainly contains Nd will be described. To do. Even when pure water is used as the liquid and the solution mainly contains Nd and the insoluble matter mainly contains Dy, Nd is recovered from the solution in the same manner as described below. Dy can be recovered from insoluble matter.

The solution mainly containing Dy can be recovered as a powder of dysprosium oxychloride by spraying it in a heated atmosphere using a spray dryer. Or after adjusting pH with respect to the solution mainly containing Dy, the insoluble matter of a hardly soluble dysprosium salt is produced | generated by adding a precipitation material.

From the solid insoluble matter, the acid chloride containing Nd can be recovered by drying it.

The insoluble matter produced by the two methods described above is filtered and dried, and then roasted at about 900 ° C. in the atmosphere, whereby Dy can be recovered as dysprosium oxide and Nd as neodymium oxide. Examples of the precipitation material include ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), ammonium hydrogen carbonate (NH ₄ HCO ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), oxalic acid (( COOH) ₂ ), sodium oxalate ((COONa) ₂ ), ammonium hydroxide (NH ₄ OH), or the like can be used.

Hereinafter, specific examples of the present invention will be described. First, in Examples 1 to 5, an example of a method for separating and recovering Nd and Dy from a mixture of neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) will be described, and then Examples 6 to 9 will be described. An embodiment of a method for separating and recovering Nd and Dy from a mixture of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) will be described.

In this example, neodymium chloride (NdCl ₃ ) was used as the rare earth chloride, and dysprosium acid chloride (DyOCl) was used as the rare earth acid chloride. Perform dissolution testing these samples, Dy separation rate _{_{(= M D / (M N}} + M D) × 100, M D is the mass of Dy in the amount of Dy and insoluble matter contained in the liquid, _{M N} is the mass of Nd ) The sample preparation method and dissolution test method are described below.

As the sample neodymium chloride (NdCl ₃ ), neodymium chloride powder having a purity of 3N manufactured by Kojundo Chemical Laboratory Co., Ltd. was used. A sample dysprosium acid chloride (DyOCl) was prepared by the following method. 3N purity dysprosium oxide and 3N purity dysprosium manufactured by Kojundo Chemical Laboratory Co., Ltd. were weighed and mixed in a glove box with an atmospheric pressure Ar gas atmosphere, and sealed in a stainless steel reaction vessel. This reaction vessel was placed in an electric furnace, and heat treatment was performed by adjusting the oxygen partial pressure and the chlorine partial pressure at point A in the chemical potential diagrams shown in FIGS. 1A and 1B. The heating temperature is 800 ° C. and the holding time is 6 hours. The powder was recovered from the reaction vessel after the heat treatment. An X-ray diffraction test was performed on the obtained powder, and it was confirmed that the crystal phase of the powder was only DyOCl.

The dissolution test was performed as follows. The produced neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) are each put in 0.25 g (total amount 0.5 g) in a glass container (60 cc), mixed with 50 cc of liquid, and stirred with a stirrer for 20 hours. did. In this example, a dissolution test using pure water as a liquid and a dissolution test using ethanol were performed. The temperature of the liquid is 25 ° C., and the stirring speed is 500 rpm. The liquid and insoluble matter after stirring were analyzed by high frequency inductively coupled plasma optical emission spectrometry (ICP-AES) to quantitatively analyze the amount of Dy and the amount of Nd.

FIG. 4 shows the amount of Dy contained in each liquid. When the liquid is pure water, Dy is contained at 800 mg / L, and when the liquid is ethanol, Dy is contained at 32 mg / L. Therefore, when the liquid is ethanol, elution of DyOCl into the liquid is suppressed as compared with the case where the liquid is pure water. That is, it can be seen that when the liquid is ethanol, the amount of DyOCl recovered as an insoluble matter is large.

FIG. 5 shows the Dy separation rate (= M _D / (M _N + M _D ) × 100, M _D is the mass of Dy, and _MN is the mass of Nd) of the insoluble matter. When the liquid is pure water, the Dy separation rate is about 94.5 mass%, and when the liquid is ethanol, the Dy separation rate is 98.8 mass%. Therefore, it can be seen that when the liquid is ethanol, the Dy separation rate is improved as compared with the case where the liquid is pure water.

From the above, it was found that when the liquid was ethanol, DyOCl was more likely to precipitate without dissolving in the liquid and the insoluble matter Dy separation rate was higher than when the liquid was pure water.

FIG. 6 shows the amount of ethanol in the liquid and the Dy separation rate of insoluble matter (= M _D / (M _N + M _D ) × 100, where M _D is the mass of Dy when a liquid in which ethanol is mixed with pure water is used. , _MN is a diagram showing a relationship with the mass of Nd). FIG. 6 shows an approximate curve of the obtained data. The amount of ethanol is expressed as a ratio of ethanol in the liquid. The sample preparation method and dissolution test method are the same as in Example 1.

As shown in FIG. 6, the Dy separation rate tended to improve as the amount of ethanol in the liquid increased. From the above, it was found that in a liquid in which pure water and ethanol were mixed, the Dy separation rate of insoluble matter was high when the amount of ethanol was large.

In this example, the dissolution test was performed by changing the mixing ratio of the sample neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl). The sample preparation method and dissolution test method are the same as in Example 1, but only the mixing ratio of neodymium chloride and dysprosium oxychloride is different from Example 1.

7, when changing the mixing ratio of neodymium chloride and dysprosium acid chlorides, Dy separation rate of insoluble matter _{_{(= M D / (M N}} + M D) × 100, M D is the mass of Dy, _{M N} Is a diagram showing the mass of Nd). FIG. 7 shows the Dy separation rate when the liquid is pure water (ethanol amount is 0 mass%) and ethanol (ethanol amount is 100 mass%). For comparison with this example, the Dy separation rate of Example 1 is also shown for the case where the liquid is pure water and ethanol. In this example, the mixing ratio of dysprosium chloride was made smaller than that in Example 1. The horizontal axis in FIG. 7 represents the amount of Dy in the sample (the ratio of Dy in the sample). The amount of Dy is 13.3 mass% in this example, and 57.6 mass% in Example 1.

As shown in FIG. 7, in this example in which the amount of Dy in the sample was reduced, the Dy separation rate of insoluble matter was lower than that in Example 1. When the liquid was pure water, the Dy separation rate greatly decreased from 94.5 mass% to 85.4 mass%. In contrast, when the liquid was ethanol, the Dy separation rate was only a small decrease from 98.8 mass% to 95.7 mass%. When the liquid was ethanol, the decrease in the Dy separation rate was not as great as when the liquid was pure water.

From the above, when the liquid is ethanol, even when the amount of Dy is small in the mixture of neodymium chloride and dysprosium oxychloride compared with the case where the liquid is pure water, the decrease in the Dy separation rate is small, and the high Dy separation rate. showed that.

In this example, a dissolution test was performed by changing the type of liquid. The sample preparation method and dissolution test method are the same as in Example 1, but only the type of liquid is different from Example 1. The liquids used in this example are pure water, ethanol, methanol, 2-propanol, acetone, and tetrahydrofuran.

FIG. 8 is a diagram showing the Dy separation rate (= M _D / (M _N + M _D ) × 100, M _D is the mass of Dy, and _MN is the mass of Nd) when the type of liquid is changed. It is. As shown in FIG. 8, when the liquid is pure water, the Dy separation rate is 94.5 mass%. On the other hand, when the liquid is an organic solvent such as ethanol, methanol, 2-propanol, acetone, or tetrahydrofuran, the Dy separation rate exceeds 97 mass%.

From the above, it was found that the Dy separation rate is higher when the liquid is an organic solvent than when the liquid is pure water.

In this example, a rare earth magnet sludge was used as the rare earth composition, and the rare earth elements were separated and recovered from the sludge. The rare earth magnet used in this example is an NdFeB magnet containing neodymium (Nd), dysprosium (Dy), or the like. The mass composition of the sludge used was 61.2% for iron (Fe), 23.1% for Nd, 3.5% for Dy, 2.0% for praseodymium (Pr), and 1.1 for boron (B). 0%.

After the sludge powder was dissolved with sulfuric acid, rare earth elements were precipitated with oxalic acid to remove components other than the rare earth elements (oxalic acid precipitation method). Next, the oxalate obtained by the oxalic acid precipitation method was heat-treated to obtain a rare earth mixed oxide. The obtained rare earth mixed oxide is heat-treated at 800 ° C. in a chlorine atmosphere, adjusted to the oxygen partial pressure and the chlorine partial pressure shown at point A in the chemical potential diagrams shown in FIGS. 1A and 1B. Neodymium chloride (NdCl ₃ ) and dysprosium chloride (DyOCl) were obtained.

50 g of the resulting mixture of neodymium chloride and dysprosium chloride was placed in ethanol (about 5 L) and stirred with a stirring blade for 20 hours. The temperature of the liquid is about 25 ° C., and the stirring speed is 200 rpm. The insoluble matter after stirring was dried at 110 ° C. for 12 hours, and then the amount of Dy and the amount of Nd were quantitatively analyzed by high frequency inductively coupled plasma emission spectroscopy (ICP-AES). When the Dy separation rate (= M _D / (M _N + M _D ) × 100, M _D is the mass of Dy, and _MN is the mass of Nd) is calculated from the obtained Dy amount and Nd amount, 98 .5%. Thus, in this example, a high Dy separation rate exceeding 95% could be obtained.

The insoluble material may be further subjected to a treatment in ethanol under the same conditions. Since there is a possibility that impurities are mixed in the insoluble material, the impurities can be further removed by this treatment. In this example, the insoluble matter was again stirred in ethanol under the same conditions, and the Dy separation rate was calculated. As a result, the Dy separation rate was 99.8%, and an extremely high value was obtained.

As described above, Dy could be separated from the rare earth composition with a high Dy separation rate of 90% or more in one separation. Nd can be recovered from a liquid (ethanol solution of neodymium chloride) as described in “(4) Recovery of Dy and Nd”. In this example, the Dy separation rate of insolubles is high, that is, the amount of Dy contained in the liquid is small, so the Nd separation rate is inevitably high.

In this example, neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) were used as rare earth acid chlorides. Perform dissolution tests on these samples, Nd amount and the amount of Dy contained in the solution, and the solution Dy separation rate _{_{(= M D / (M N}} + M D) × 100, M D is the mass of Dy, _{M N} is Nd Mass). The sample preparation method and dissolution test method are described below.

As a sample, neodymium acid chloride (NdOCl) uses neodymium oxide with a purity of 3N and neodymium chloride with a purity of 3N manufactured by Kojundo Chemical Laboratory Co., Ltd., and oxidation with a purity of 3N for dysprosium acid chloride (DyOCl). Using dysprosium and dysprosium chloride having a purity of 3N, the following methods were used. A mixed powder of neodymium oxide and neodymium chloride and a mixed powder of dysprosium oxide and dysprosium chloride were weighed and mixed in a glove box in an atmospheric pressure Ar gas atmosphere, and each was sealed in a stainless steel reaction vessel. These reaction vessels are put in an electric furnace, and under the conditions of generating NdOCl and DyOCl (oxygen partial pressure and chlorine partial pressure in a region where NdOCl and DyOCl are stable) in the chemical potential diagrams shown in FIGS. 1A and 1B, respectively. Heat treatment was performed. The heating temperature is 800 ° C. and the holding time is 6 hours. The powder was recovered from the reaction vessel after the heat treatment. An X-ray diffraction test was performed on the obtained two types of powders to examine the crystal phase of the powders.

9 and 10 show X-ray diffraction patterns of these powders as a result of the X-ray diffraction test of the powders obtained by this heat treatment. FIG. 9 is an X-ray diffraction pattern of a powder obtained by heat treatment of a mixed powder of neodymium oxide and neodymium chloride. FIG. 10 is an X-ray diffraction pattern of a powder obtained by heat-treating a mixed powder of dysprosium oxide and dysprosium chloride. 9 shows an X-ray diffraction pattern of NdOCl by ICDD (International Center for Diffraction Data), which is a standard collection of powder X-ray diffraction, and FIG. 10 shows an X-ray diffraction pattern of DyOCl by ICDD. It is written together below the X-ray diffraction pattern obtained in the test.

As shown in FIG. 9, only NdOCl was produced from the mixed powder of neodymium oxide and neodymium chloride. Further, as shown in FIG. 10, only DyOCl was produced from the mixed powder of dysprosium oxide and dysprosium chloride.

These acid chlorides were placed in a liquid and a dissolution test was performed to evaluate the solubility in the liquid. The evaluation method is as follows. The produced acid chlorides (NdOCl and DyOCl) were each put in 0.25 g (total amount 0.5 g) into a glass container (60 cc), and 50 cc of the liquid was mixed. The rotor placed in this glass container was stirred with a stirrer at a rotation speed of 500 rpm for 20 hours. The stirred solution is filtered through a filter paper (particle holding capacity 2.5 μm) and a syringe filter (pore diameter 0.2 μm), and then the filtrate (hereinafter referred to as a solution) is subjected to high frequency inductively coupled plasma emission spectroscopy (ICP−). AES) and the amount of Dy and the amount of Nd dissolved in the liquid were quantitatively analyzed. In this example, a dissolution test using pure water as a liquid and a dissolution test using a mixed solution of pure water and ethanol were performed.

FIG. 11 is a diagram showing the Nd amount and Dy amount of the solution when the amount of ethanol in the liquid is changed. In FIG. 11, an approximate curve of the obtained data is displayed. The amount of ethanol is expressed as a ratio of ethanol in the liquid. When the amount of ethanol is 100 mass%, the liquid is only ethanol, and when the amount of ethanol is 0 mass%, the liquid is pure water. The amount of Nd decreased as the amount of ethanol increased, and when the liquid was ethanol alone, it decreased to about 1/1000 of that when the liquid was pure water. The amount of Dy gradually decreased with the increase in the amount of ethanol up to about 60 mass%, but decreased significantly when the amount of ethanol exceeded about 60 mass%. Shows a value of about 1/150 in the case of pure water.

As shown in FIG. 11, NdOCl and DyOCl have different dissolution behavior with respect to the amount of ethanol. From the Nd amount and Dy amount of the solution shown in FIG. 11, the Dy separation rate of the solution (= M _D / (M _N + M _D ) × 100, M _D is the mass of Dy, and _MN is the mass of Nd) did.

FIG. 12 is a diagram showing the Dy separation rate calculated from the Nd amount and Dy amount of the solution. As shown in FIG. 12, the Dy separation rate increased as the amount of ethanol increased, and showed a maximum value when the amount of ethanol was around 60%. Further, the Dy separation rate was 80% or more when the amount of ethanol was 30% or more, and particularly 90% or more when the amount of ethanol was in the range of 50% to 80%.

From the above, it was found that when the amount of ethanol in the liquid (ratio of ethanol and pure water in the liquid) is in the range of 50% to 80%, the Dy separation rate shows a value of 90% or more.

In this example, dissolution tests were performed by changing the particle sizes of neodymium acid chloride (NdOCl) and dysprosium acid chloride (DyOCl) as samples. The sample preparation method and dissolution test method were the same as in Example 6. However, the particle diameters of NdOCl and DyOCl were changed by changing the heat treatment conditions. As the liquid, a mixed solution in which 50% ethanol was mixed with pure water was used.

FIG. 13 is a diagram showing the relationship between the particle size of NdOCl and the Nd amount of the solution, and the relationship between the particle size of DyOCl and the Dy amount of the solution. In FIG. 13, an approximate curve of the obtained data is displayed. As shown in FIG. 13, both NdOCl and DyOCl showed a tendency that the Nd amount and Dy amount of the solution respectively decreased as the particle size increased. However, elution behavior is different between NdOCl and DyOCl. In the case of NdOCl, when the particle size was 3 μm or more, the Nd content of the solution was below the detection limit of high frequency inductively coupled plasma optical emission spectrometry (ICP-AES). In contrast, with DyOCl, Dy was detected from the solution even with a particle size of 10 μm.

14, when changing the particle size of the NdOCl and DyOCl, Dy separation rate was calculated from the Nd amount and Dy of the solution ₍₌ the _{_{M D / (M N + M}} D) × 100, M D is Dy It is a figure which shows mass and _MN is the mass of Nd). In FIG. 14, when the particle size is 3 μm or more, the detection limit value of ICP-AES was used as the Nd amount of the solution.

As shown in FIG. 14, the Dy separation rate was 90% or more when the particle size was in the range of about 0.5 μm to about 8 μm. In particular, when the particle size was in the range of 1 μm to 5 μm, the Dy separation rate showed a high value of 95% or more.

From the above, it was found that the Dy separation rate showed a high value of 95% or more when the particle diameters of NdOCl and DyOCl were in the range of 1 μm to 5 μm.

In this example, a dissolution test was performed by changing the type of liquid. The sample preparation method and dissolution test method are the same as in Example 6, but only the type of liquid is different from Example 6. The liquid used in this example is pure water and a mixed liquid in which 50% of various organic solvents are mixed with pure water. As the organic solvent, methanol, ethanol, 2-propanol, acetone, and tetrahydrofuran were used.

FIG. 15 is a diagram showing the Nd amount and Dy amount of the solution when the type of liquid is changed. As shown in FIG. 15, when the liquid is pure water, the Dy amount of the solution is smaller than the Nd amount, but when the liquid is a mixed solution of pure water and an organic solvent, the Dy amount of the solution is smaller than the Nd amount. Increased. Moreover, when the liquid was a mixed liquid, it was found that the difference between the Dy amount and the Nd amount of the solution was large, and the difference in solubility between the two in the liquid appeared remarkably. For this reason, when the liquid is a mixed liquid of pure water and an organic solvent, it is expected that the Dy separation rate of the solution increases.

FIG. 16 shows the Dy separation rate (= M _D / (M _N + M _D ) × 100 calculated from the Nd amount and Dy amount of the solution when the type of liquid is changed, where M _D is the mass of Dy, M _N Is a diagram showing the mass of Nd). As shown in FIG. 16, any mixed solution showed a higher Dy separation rate than pure water. In a mixed solution using methanol, ethanol, 2-propanol, or acetone as an organic solvent, the Dy separation rate is 90% or more. In particular, in a mixed solution using methanol, the Dy separation rate is 95% or more. High value.

From the above, it was found that when a mixed solution in which 50% of an organic solvent was mixed with pure water was used as a liquid, the Dy separation rate showed a value of 90% or more.

After the sludge powder was dissolved in sulfuric acid, rare earth elements were precipitated with oxalic acid to remove components other than the rare earth elements (oxalic acid precipitation method). Next, the oxalic oxide obtained by the oxalic acid precipitation method was heat-treated to obtain a rare earth mixed oxide. Based on the chemical potential diagrams shown in FIG. 1A and FIG. 1B, the neodymium oxychloride (NdOCl) and dysprosium oxychloride (DyOCl) are stable in the chlorine atmosphere. The oxygen partial pressure and the chlorine partial pressure were adjusted, and heat treatment was performed at 800 ° C. to obtain neodymium acid chloride and dysprosium acid chloride.

50 g of a mixture of the obtained neodymium acid chloride and dysprosium acid chloride was placed in a mixed solution (about 5 L) in which pure water was mixed with 50% ethanol, and stirred with a stirring blade for 20 hours. The temperature of the liquid is about 25 ° C., and the stirring speed is 200 rpm. The stirred solution was filtered in the same manner as in Example 6, and the Nd amount and Dy amount were quantitatively analyzed by high frequency inductively coupled plasma emission spectroscopy (ICP-AES). The Dy separation rate (= M _D / (M _N + M _D ) × 100, M _D is the mass of Dy, and _MN is the mass of Nd) is calculated from the obtained Nd amount and Dy amount. It was 6%. Thus, in this example, a high Dy separation rate exceeding 95% could be obtained.

As described above, Dy could be separated from the rare earth composition with a high Dy separation rate of 90% or more in one separation. As described in “(4) Recovery of Dy and Nd”, Nd can be recovered from a solid insoluble matter. In this embodiment, the Dy separation rate of the solution is high, that is, the amount of Dy contained in the liquid is large, so that the Nd separation rate is inevitably high.

In the above embodiment, the case where the rare earth composition contains two types of rare earth elements has been described. When three or more kinds of rare earth elements are contained in the rare earth composition, the separation and recovery method similar to the above may be repeated to separate and collect the rare earth elements one by one. In this manner, each rare earth element can be separated and recovered from the rare earth composition containing a plurality of types of rare earth elements.

Claims

A method for separating and recovering multiple types of rare earth elements,
A mixture containing a rare earth acid chloride and a rare earth chloride, and the liquid mixture containing the rare earth acid chloride from a rare earth element of a type different from the rare earth element constituting the rare earth chloride. Obtaining an insoluble matter containing the rare earth acid chloride and a liquid in which the rare earth chloride is dissolved;
Recovering the rare earth acid chloride from the insoluble matter;
Recovering the rare earth chloride from the liquid in which the rare earth chloride is dissolved;
A method for separating and recovering rare earth elements, comprising:
A method for separating and recovering multiple types of rare earth elements,
A mixture comprising a rare earth acid chloride and a rare earth chloride, wherein the rare earth acid chloride is composed of a rare earth element different from the rare earth element constituting the rare earth chloride, and includes an organic solvent. Obtaining an insoluble material containing the rare earth acid chloride and a liquid in which the rare earth chloride is dissolved by placing the liquid in a liquid;
Recovering the rare earth acid chloride from the insoluble matter;
Recovering the rare earth chloride from the liquid in which the rare earth chloride is dissolved;
A method for separating and recovering rare earth elements, comprising:
A method for separating and recovering multiple types of rare earth elements,
The first rare earth acid chloride is a mixture containing a first rare earth acid chloride and a second rare earth acid chloride from a rare earth element different from the rare earth element constituting the second rare earth acid chloride. Obtaining a liquid in which the first rare earth acid chloride is dissolved by putting the mixture in which the product is composed into a liquid;
Recovering the first rare earth acid chloride from the liquid in which the first rare earth acid chloride is dissolved;
Recovering the second rare earth acid chloride from the insoluble matter not dissolved in the liquid;
A method for separating and recovering rare earth elements, comprising:
A method for separating and recovering multiple types of rare earth elements,
The first rare earth acid chloride is a mixture containing a first rare earth acid chloride and a second rare earth acid chloride from a rare earth element different from the rare earth element constituting the second rare earth acid chloride. A step of obtaining a liquid in which the first rare earth acid chloride is dissolved by putting the mixture in which the product is constituted into a liquid containing an organic solvent;
Recovering the first rare earth acid chloride from the liquid in which the first rare earth acid chloride is dissolved;
Recovering the second rare earth acid chloride from the insoluble matter not dissolved in the liquid;
A method for separating and recovering rare earth elements, comprising:
5. The method for separating and collecting rare earth elements according to claim 2 or 4, wherein the organic solvent is an alcohol.
3. The method for separating and collecting rare earth elements according to claim 1 or 2, wherein the rare earth oxychloride is an acid chloride containing dysprosium.
3. The method for separating and collecting rare earth elements according to claim 1 or 2, wherein the rare earth chloride is a chloride containing neodymium.
5. The method for separating and collecting rare earth elements according to claim 3 or 4, wherein the first rare earth oxychloride is an acid chloride containing dysprosium.
5. The method for separating and collecting rare earth elements according to claim 3 or 4, wherein the second rare earth acid chloride is an acid chloride containing neodymium.
A method for separating and recovering multiple types of rare earth elements,
By heating the composition containing a plurality of types of rare earth elements in a chlorine atmosphere, the mixture includes a rare earth oxychloride and a rare earth chloride, and the rare earth elements different from the rare earth elements constituting the rare earth chloride Producing the mixture comprising the rare earth acid chloride from an element;
Obtaining the insoluble matter containing the rare earth acid chloride and the liquid in which the rare earth chloride is dissolved by placing the mixture in a liquid;
Recovering the rare earth acid chloride from the insoluble matter;
Recovering the rare earth chloride from the liquid in which the rare earth chloride is dissolved;
A method for separating and recovering rare earth elements, comprising:
A method for separating and recovering multiple types of rare earth elements,
By heating the composition containing a plurality of types of rare earth elements in a chlorine atmosphere, the mixture includes a rare earth oxychloride and a rare earth chloride, and the rare earth elements different from the rare earth elements constituting the rare earth chloride Producing the mixture comprising the rare earth acid chloride from an element;
Placing the mixture in a liquid containing an organic solvent to obtain an insoluble matter containing the rare earth acid chloride and a liquid in which the rare earth chloride is dissolved;
Recovering the rare earth acid chloride from the insoluble matter;
Recovering the rare earth chloride from the liquid in which the rare earth chloride is dissolved;
A method for separating and recovering rare earth elements, comprising:
A method for separating and recovering multiple types of rare earth elements,
A composition containing a first rare earth acid chloride and a second rare earth acid chloride by heating the composition containing the plurality of rare earth elements in a chlorine atmosphere, and the second rare earth acid chloride. Forming the mixture in which the first rare earth acid chloride is constituted from a rare earth element different from the rare earth element constituting
Obtaining a liquid in which the first rare earth acid chloride is dissolved by placing the mixture in a liquid;
Recovering the first rare earth acid chloride from the liquid in which the first rare earth acid chloride is dissolved;
Recovering the second rare earth acid chloride from the insoluble matter not dissolved in the liquid;
A method for separating and recovering rare earth elements, comprising:
A method for separating and recovering multiple types of rare earth elements,
A composition containing a first rare earth acid chloride and a second rare earth acid chloride by heating the composition containing the plurality of rare earth elements in a chlorine atmosphere, and the second rare earth acid chloride. Forming the mixture in which the first rare earth acid chloride is constituted from a rare earth element different from the rare earth element constituting
Obtaining a liquid in which the first rare earth acid chloride is dissolved by placing the mixture in a liquid containing an organic solvent;
Recovering the first rare earth acid chloride from the liquid in which the first rare earth acid chloride is dissolved;
Recovering the second rare earth acid chloride from the insoluble matter not dissolved in the liquid;
A method for separating and recovering rare earth elements, comprising:
14. The method for separating and collecting rare earth elements according to claim 11 or 13, wherein the organic solvent is an alcohol.
12. The method for separating and collecting rare earth elements according to claim 10 or 11, wherein the rare earth oxychloride is an acid chloride containing dysprosium.
12. The method for separating and collecting rare earth elements according to claim 10 or 11, wherein the rare earth chloride is a chloride containing neodymium.
14. The method for separating and collecting rare earth elements according to claim 12 or 13, wherein the first rare earth oxychloride is an acid chloride containing dysprosium.
14. The method for separating and collecting rare earth elements according to claim 12 or 13, wherein the second rare earth acid chloride is an acid chloride containing neodymium.